1. Field of the Invention
The present invention relates to an actuating device for an electrical switch device, such as for example a circuit breaker. The invention also relates to an electrical switch device incorporating such an actuating device. The actuating device is for example remote with respect to the electrical switch device.
2. Description of the Prior Art
For safety reasons, the locking of the hand lever of an actuating device for an electrical switch device must be possible only when the hand lever is in the “Off” position. For this purpose, it is known to provide the actuating device with a device for locking the hand lever when the latter is in the “Off” position. In order to maintain the hand lever in the locked position, padlocks are hooked though one or more openings formed on the hand lever. The U.S. Pat. No. 6,423,912 describes such a locking device in particular.
However, when the contacts of the electrical switch device are welded to each other as the result, for example, of a short circuit, the rotational locking of the hand lever in the “Off” position must be made impossible given that an operator could believe that the contacts are open whereas in reality the latter are closed because they are welded.
The U.S. Pat. No. 6,797,903 and U.S. Pat. No. 5,222,382 (or the corresponding EP 0 450 699) describe solutions making it possible to prevent such a situation. In these patents, the rotation of the hand lever towards its “Off” position whilst the contacts are welded together causes the rotation of an element that comes to obturate the passage through which a locking device must pass. Even if the operator forces the hand lever in order to return it to the “Off” position, locking remains impossible.
However, by forcing the hand lever in order to attempt to return it into its off position whilst the contacts are welded together, the operator can damage the hand lever and the electrical switch device. Moreover, if by forcing the hand lever the operator succeeds in unsticking the contacts, he risks creating electrical arcs which can prove to be dangerous.
The document EP 0 472 477 describes a device for locking a circuit breaker handle when the contacts are welded. When the contacts are welded, after passing through a dead point by manual action, the handle becomes immobilized and is locked in a stable intermediate position, situated between the open position and the closed position. In this intermediate position, a deformable part deforms under the action of the handle such that it comes to butt against a fixed stop piece of the device.
In such a device, the deformable part is particularly stressed and it carries out the double function of detection of the torque when an operator attempts to return the handle towards the open position whilst the contacts are welded and of limiting the torque by blocking the rotation of the handle against the fixed stop when the contacts are welded. The part must thus exhibit both a certain flexibility and a certain rigidity in order to carry out both functions. Moreover, when there is a welding of the contacts, in the intermediate position of the handle, the deformable part is stressed permanently, which can cause a return to the open position if the part is worn even though the contacts are welded.